Planetary gear train for transmission of motor

ABSTRACT

Provided is a planetary gear train for transmission of e-bike motor, including: a carrier protrusively formed in a center with a stator axis insertion boss provided with a stator axis insertion groove in a shape corresponding to that of the stator axis for insertion of the stator axis, and mounted with a plurality of gear installation units; a plurality of planetary gears interposed rotatably mounted at an upper surface of the gear installation unit of the carrier; and a fixing pin rotatably mounting the plurality of planetary gears on the gear installation units, wherein the fixing pin includes a pin head inhibiting the planetary gears from deviating

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119 of KoreanPatent Application Nos. 10-2011-0071844, filed Jul. 20, 2011, and10-2011-0072975, filed Jul. 22, 2011, which are hereby incorporated byreference in their entirety,

BACKGROUND Field of Invention

The present disclosure relates to a planetary gear train fortransmission of e-bike motor,

Background

The pedal cycle may be, for example, a conventional pedal cycle in whichdrive is only ever provided by a cyclist applying force to the pedalsthereof, such cycles sometimes being referred to as “push bikes”.

Recently, the pedal cycle has evolved to, for example, a pedelec, anEAPC (electrically-assisted pedal cycle) an electric bicycle or ane-bike. The electrically-assisted pedal cycle (EAPC) or an e-bike isoperated by a motor in such a manner that electrical power is used toassist the efforts of a cyclist pedaling the cycle.

Several methods of arranging a motor have been attempted and a recentmethod is to embed a motor and a transmission inside a hub forming afront wheel or a rear wheel. The hub is integrally formed with the motorand the transmission therein.

The hub includes a hub housing and a stationary shaft. The motor isarranged inside the hub housing, and the stationary shaft is fixed to afront wheel or a rear wheel of a frame of an e-bike or an e-scooter. Asa result, the hub housing is rotated relative to the stationary shaft torotate a wheel of the bike coupled to the hub housing.

The motor is housed inside the hub housing to rotate a rotation shaft bymeans of the electromagnetic interaction. The motor housing of the motoris fixed relative to the hub housing, and the rotation shaft rotativelyarranged in the center of the motor housing transmits a turning effectto a sun gear integrally formed at a distal end thereof, whereby a poweris supplied to a transmission including the sun gear.

The transmission is provided with a planetary gear meshed with the sungear, a margin of the transmission is arranged with a ring gear to meshwith the planetary gear, whereby the transmission receives the turningeffect of the rotation shaft in a reduced speed.

Generally, four planetary gears are provided in a pair and rotatablymounted on a carrier to form a planetary gear train. The planetary geartrain is formed in such a manner that four planetary gears are rotatablyand respectively mounted on a one-bodied carrier using bearings, washersand fixing pins formed on upper and bottom surfaces of the bearing, anda stopper is formed at one surface of the carrier to inhibit therespective fixing pins from axially being displaced. Thus, the planetarygear module needs a total of 22 parts including one carrier, onestopper, four planetary gears, bearings, pins and eight washers.

Meanwhile, problems frequently occur in which a washer is lost in thecourse of coupling the bearings to pins in the assembly process, or theassembly process is advanced with the washer missing due to mistake byan operator, and if the washer is missing in the assembly process,problems may occur in which the fixing pin is detached when deformationis generated by external force.

Another problem is that a manufacturing cost of the one-bodied carrieris very high due to complicated processing method, and the one-bodiedcarrier cannot be manufactured through a relatively inexpensivesintering or die casting process.

BRIEF SUMMARY

The present disclosure has been made to solve the foregoing problems ofthe prior art and therefore an object of certain embodiments of thepresent invention is to provide a structure-improved and manufacturingcost-reduced planetary gear train for transmission of e-bike motor byreducing the number of parts and diversifying a manufacturing method.

In one general aspect of the present disclosure, there is provided aplanetary gear train for transmission of e-bike motor, the planetarygear train comprising: a first carrier protrusively formed in a centerwith a stator axis insertion boss provided with a stator axis insertiongroove in a shape corresponding to that of the stator axis for insertionof the stator axis, and mounted with a plurality of first gearinstallation units; a second carrier formed with a second gearinstallation unit at a position corresponding to that of the first gearinstallation unit of the first carrier, and mounted in a center with aboss insertion hole penetratively coupled by the stator axis insertionboss; a plurality of planetary gears interposed between the first andsecond installation units of the first and second carriers; and a fixingpin rotatably fixing the plurality of planetary gears on the first andsecond gear installation units.

Preferably, but not necessarily, the planetary gear train fortransmission of e-bike motor further includes a bearing centrallyarranged on the plurality of the planetary gears, where an outer ring iscentrally fixed at the planetary gear and an inner ring is coupled bythe fixing pin.

Preferably, but not necessarily, the first and second gear installationunits include first and second pin holes each having a diametercorresponding to that of the fixing pin, and first and second supportrings protrusively formed at a surface opposite to the planetary gear,and centrally and respectively arranged with first and second pin holes.

Preferably, but not necessarily, the planetary gear is centrally formedwith a bearing accommodation hole having a diameter corresponding tothat of the outer ring of the bearing.

Preferably, but not necessarily, the inner ring of the bearing includesthe fixing pin and a bearing pin hole having a size corresponding to thediameter of the first and second pin hole coupled to the fixing pin.

Preferably, but not necessarily, the first and second support ringsrespectively support the inner ring of the bearing.

Preferably, but not necessarily, the first and second carriers areprovided in a cross (+) shape with four directions being symmetrical,centrally and respectively provided with the stator axis insertion bossand the boss insertion hole, and the first and second gear installationunits are provided at four protrusive distal ends to allow fourplanetary gears to be rotatably mounted.

In another general aspect of the present disclosure, there is provided aplanetary gear train for transmission of e-bike motor, the planetarygear train comprising: a carrier protrusively funned in a center with astator axis insertion boss provided with a stator axis insertion groovein a shape corresponding to that of the stator axis for insertion of thestator axis, and mounted with a plurality of gear installation units; aplurality of planetary gears interposed rotatably mounted at an uppersurface of the gear installation unit of the carrier; and a fixing pinrotatably mounting the plurality of planetary gears on the gearinstallation units, wherein the fixing pin includes a pin headinhibiting the planetary gears from deviating.

Preferably, but not necessarily, the planetary gear train fortransmission of e-bike further includes a bearing centrally arranged onthe plurality of the planetary gears, where an outer ring is centrallyfixed at the planetary gear and an inner ring is coupled by the fixingpin.

Preferably, but not necessarily, the gear installation units include apin hole having a diameter corresponding to that of the fixing pin, asupport ring protrusively formed at a surface opposite to the planetarygear, and centrally arranged with the pin hole, and a through holehaving a diameter smaller than that of the pin hole and formed with apin support unit at a center of the pin hole.

Preferably, but not necessarily, the planetary gear is centrally formedwith a bearing accommodation hole having a diameter corresponding tothat of the outer ring of the bearing.

Preferably, but not necessarily, the inner ring of the bearing includesthe fixing pin and a bearing pin hole having a size corresponding to thediameter of the pin hole coupled to the fixing pin.

Preferably, but not necessarily, the support ring supports the innerring of the bearing.

Preferably, but not necessarily, the carrier is provided in a cross (+)shape with four directions being symmetrical, centrally provided withthe stator axis insertion boss, and the gear installation unit isprovided at four protrusive distal ends to allow four planetary gears tobe rotatably mounted.

The planetary gear train for transmission of e-bike motor according tothe present disclosure has an advantageous effect in that a carrier canbe manufactured in various methods to reduce a manufacturing cost ofparts, and to reduce assembleability and parts cost due to reducednumber of parts involved in the assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing figures depict one or more implementations in accord withthe present concepts, by way of example only, not by way of limitations.In the figures, like reference numerals refer to the same or similarelements.

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, also illustrate embodiment(s) of thedisclosure, and together with the description serve to explain theprinciple of the disclosure. In the drawings:

FIG. 1 is a lateral cross-sectional view illustrating a generalstructure of an e-bike motor according to the present disclosure;

FIG. 2 is a perspective view of a planetary gear train of FIG. 1according to a first exemplary embodiment of the present disclosure;

FIG. 3 is an exploded perspective view of a planetary gear module of ane-bike according to an exemplary embodiment of the present disclosure;

FIG. 4 is a cross-sectional view taken along line A-A of FIG. 2;

FIG. 5 is a perspective view of a planetary gear train of FIG. 1according to another exemplary embodiment of the present disclosure;

FIG. 6 is an exploded perspective view of a planetary gear module of anc-bike according to a second exemplary embodiment of the presentdisclosure; and

FIG. 7 is a cross-sectional view taken along line B-B of FIG. 5.

DETAILED DESCRIPTION

The disclosed embodiments and advantages thereof are best understood byreferring to FIGS. 1-7 of the drawings, like numerals being used forlike and corresponding parts of the various drawings. Other features andadvantages of the disclosed embodiments will be or will become apparentto one of ordinary skill in the art upon examination of the followingfigures and detailed description. It is intended that all suchadditional features and advantages be included within the scope of thedisclosed embodiments, and protected by the accompanying drawings.Further, the illustrated figures are only exemplary and not intended toassert or imply any limitation with regard to the environment,architecture, or process in which different embodiments may beimplemented. Accordingly, the described aspect is intended to embraceall such alterations, modifications, and variations that fall within thescope and novel idea of the present invention.

Meanwhile, the terminology used herein is for the purpose of describingparticular implementations only and is not intended to be limiting ofthe present disclosure. The terms “first”, “second”, and the like,herein do not denote any order, quantity, or importance, but rather areused to distinguish one element from another. For example, a secondconstituent element may be denoted as a first constituent elementwithout departing from the scope and spirit of the present disclosure,and similarly, a first constituent element may be denoted as a secondconstituent element.

As used herein, the terms “a” and “an” herein do not denote a limitationof quantity, but rather denote the presence of at least one of thereferenced item. That is, as used herein, the singular forms “a”, “an”and “the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present.

It will be further understood that the terms “comprises” and/or“comprising”, or “includes” and/or “including” when used in thisspecification, specify the presence of stated features, regions,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,regions, integers, steps, operations, elements, components, and/orgroups thereof.

Also, “exemplary” is merely meant to mean an example, rather than thebest. If is also to be appreciated that features, layers and/or elementsdepicted herein are illustrated with particular dimensions and/ororientations relative to one another for purposes of simplicity and easeof understanding, and that the actual dimensions and/or orientations maydiffer substantially from that illustrated.

That is, in the drawings, the size and relative sizes of layers, regionsand/or other elements may be exaggerated or reduced for clarity. Likenumbers refer to like elements throughout and explanations thatduplicate one another will be omitted.

Hereinafter, a planetary gear train for transmission of e-bike motoraccording to exemplary embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings.

FIG. 1 is a lateral cross-sectional view illustrating a generalstructure of an e-bike motor according to the present disclosure.

Referring to FIG. 1, an e-bike includes a hub housing 11, a motor 20 anda transmission 30.

The hub housing 11 takes an approximately cylindrical shape, and isarranged at a center axis of a front wheel or a rear wheel of the bike.The hub housing 11 may be arranged at a periphery with a bike wheelmember, or may be coupled to a hub housing accommodation groove formedat an inner wheel of bike wheel.

Meanwhile, the hub housing 11 is centrally formed with a fixing axis 22,The fixing axis 22 is fixed at a front wheel or a rear wheel side of aframe of an e-bike or an e-scooter. Thus, the hub housing 11 is rotatedrelative to the fixing axis 22 to rotate the wheel of the bike coupledto the hub housing 11.

The motor 20 is concentrically mounted with the fixing axis 22 insidethe hub housing 11. The motor 20 includes a rotor 21 a and a stator 21b, and the rotor 21 a is centrally mounted with a rotation shaft 21 c.The rotation shaft 21 c is concentrically mounted with the fixing axis22, and is mounted at a distal end with a sun gear 30.

The sun gear 30 rotates by receiving a turning effect of the rotationshaft 21 c generated by interaction of the rotor 21 a mounted inside themotor housing 21 and the stator 21 b.

A first planetary gear 40 is meshed with the sun gear 30 to rotate inassociation with rotation of the sun gear 30. At least three firstplanetary gears 40 are provided, and a periphery of the planetary gear40 is meshed by a first ring gear 50. The first ring gear 50 is rotatedin association with rotation of the first planetary gears 40. The firstring gear 50 is arranged at a periphery with a second ring gear 60,where the second ring gear 60 is rotated by being coupled to a hub cover12 forming an exterior look of a distal end of the hub housing 11.

A connection member is interposed between the first ring gear 50 and thesecond ring gear 60 to directly transmit or block a turning effect inresponse to a rotation direction.

For example, the rotation of the first ring gear 50 is directlytransmitted to the second ring gear 60 by the connection member, in caseof rotation to one direction of the rotation shaft, and the housing isrotated by rotation of the hub gear 12 coupled to the second ring gear60.

Meantime, in case of rotation to the other direction of the rotationshaft, the direct transfer of the turning effect to the second ring gear60 of the first ring gear 50 is blocked, and change and transfer ofrotation direction is performed by a planetary gear train 100concentrically supported by a stator shaft 101 via the connection memberto rotate the second ring gear 60 to a direction.

According to a first exemplary embodiment of the present disclosure, theplanetary gear train 100 includes first and second carriers 110, 120,second planetary gears 130 and a fixing pin 140, as illustrated in FIGS.2, 3 and 4.

The first carrier 110 takes an approximate shape of a plate, andpreferably takes a cross (+) shape with four directions beingsymmetrical, as shown in FIGS. 2 and 3, which is to mount a total offour second planetary gears 130, where each protrusive distal end isprovided with a first gear installation unit 115 for mounting the secondplanetary gear 130.

The first carrier 110 is centrally and protrusively formed with a statoraxis insertion boss 112 formed with a stator axis insertion groove 111having a shape corresponding to a diameter of the stator axis 101. Thestator axis insertion groove 111 is protrusively formed at an innersurface with a plurality of slip inhibition ribs 113 supporting a fixedposition and inhibiting the stator axis 101 from running idle to adirection parallel to an insertion direction.

The first gear installation unit 115 is formed at a distal end of thefirst carrier 110 to allow the second planetary gear 130 to rotate, andincludes a first pin hole 113 insertedly coupled by a fixing pin 140fixedly and rotatably supporting the second planetary gear 130, and afirst support ring 114 centrally having the first pin hole 113 andprotruded at a predetermined height.

The first support ring 114 functions in the same way as that of aconventional washer member, and preferably, supports an inner ring 152of a bearing 150 coupled to the second planetary gear (130, describedlater).

The second carrier 120 takes an approximate shape of a plate, andpreferably takes a cross (+) shape with four directions beingsymmetrical, as shown in FIGS. 2 and 3, which is to mount a total offour second planetary gears 130, where each protrusive distal end isprovided with a second gear installation unit 125 for mounting thesecond planetary gear 130.

The second carrier 120 is centrally formed with a boss insertion hole122 press-fitted by the stator axis insertion boss 112 coupled with thestator axis 101.

The second gear installation unit 125 is formed at a distal end of thesecond carrier 120 to allow the second planetary gear 130 to rotate, andincludes a second pin hole 123 insertedly coupled by the fixing pin 140fixedly and rotatably supporting the second planetary gear 130, and asecond support ring 124 centrally having the second pin hole 123 andprotruded at a predetermined height.

The second support ring 124 functions in the same way as that of aconventional washer member, and preferably, supports an inner ring 152of a bearing 150 coupled to the second planetary gear (130, describedlater).

The second planetary gear 130 is rotatably mounted on the first andsecond gear installation units 115, 125 each provided at the first andsecond carriers 110, 120. The second planetary gear 130 is meshed withthe second ring gear 60 to block the rotation of the second ring gear60.

The second planetary gear 130 is formed at a periphery with a gear tooth131, and is formed at an inner surface with a bearing accommodation hole152 coupled with an outer ring 151 of the bearing 150. A diameter of thebearing accommodation hole 152 is same as that of the outer ring 151 ofthe bearing 151.

Meanwhile, the bearing 150 is provided to minimize a friction generatedwhen the second planetary gear 130 is rotated, and includes an outerring 151 and an inner ring 152. A ball member is interposed between theouter ring and the inner ring 151, 152, and serves to smooth a relativerotation between the outer ring 151 and the inner ring 152.

The inner ring 152 is centrally formed with a bearing pin hole 153having a diameter corresponding to that of the fixing pin 140. Althoughthe present disclosure has exemplified the bearing 150 as a ballbearing, the present disclosure is not limited thereto, and other typesof bearings including an air bearing and a magnetic bearing may be used,when the need arises.

The fixing pin 140 is insertedly coupled from an inner side toward anouter side of the first and second pin holes 113, 123 penetrativelyformed at the first and second gear installation units 115, 125 eachprovided at the first and second carriers 110, 120. At this time, distalends of the first and second pin holes 113, 123 are formed with firstand second through holes 116, 126 each having a diameter smaller thanthat of the first and second pin holes 113, 123, such that the fixingpin 140 cannot penetrate the first and second pin holes 113, 123. Thus,the fixing pin 140 interposed between the first and second carriers 110,120 is not feared to deviate to an axial direction, even if a separatestopper is not installed.

Furthermore, the fixing pin 140 is penetratively coupled to the bearingpin hole 153 centrally formed at the inner ring 152 of the bearing 150to supportively and rotatably fix the second planetary gear 130, andboth ends of the fixing pin 140 are coupled to the first and second pinholes 113, 123 to fix the first and second carriers 110, 120, In orderto insertively couple the both ends of the fixing pin 140 to the firstand second carriers 110, 120, there is a need of press-fitting byperforming a press-fit process.

That is, the planetary gear train 100 according to the presentdisclosure arranges the first and second carriers 110, 120, the secondplanetary gear 130 mounted with the bearing 150 and the fixing pin 140at each assembly position. Furthermore, the bearing 150 is press-fittedto the center of the second planetary gear 130, the fixing pin 140 ispenetratively coupled to the bearing pin hole 153 centrally formed atthe inner ring 152 of the bearing 150, the second planetary gears 130where a total of four bearing pin hole 153 is press-fitted by the fixingpin 140 are arranged on the first and second gear installation units115, 125 of the first carrier 110 or the second carrier 120, and bothends of the fixing pin 140 is press-fitted from an inner side toward theouter side of the first and second carriers 110, 120.

According to the second exemplary embodiment of the present disclosure,the planetary gear train 100 may include a carrier 110, second planetarygears 130 and the fixing pin 140, as illustrated in FIGS. 5, 6 and 7.

The carrier 110 takes an approximate shape of a plate, and preferablytakes a cross (+) shape with four directions being symmetrical, as shownin FIGS. 5 and 6, which is to mount a total of four second planetarygears 130, where each protrusive distal end is provided with a secondgear installation unit 125 for mounting the second planetary gear 130.

The carrier 110 is centrally and protrusively formed with a stator axisinsertion boss 112 formed with a stator axis insertion groove 111 havinga shape corresponding to a diameter of the stator axis 101. The statoraxis insertion groove 111 is protrusively formed at an inner surfacewith a plurality of slip inhibition ribs 113 supporting a fixed positionand inhibiting the stator axis 101 from running idle to a directionparallel to an insertion direction.

The gear installation unit 115 is formed at a distal end of the carrier110 to allow the second planetary gear 130 to rotate, and includes afirst pin hole 113 insertedly coupled by the fixing pin 140 fixedly androtatably supporting the second planetary gear 130, and a first supportring 114 centrally having the first pin hole 113 and protruded at apredetermined height.

The first support ring 114 functions in the same way as that of aconventional washer member, and preferably, supports an inner ring 152of a bearing 150 coupled to the second planetary gear (130, describedlater).

The second planetary gear 130 is rotatably mounted on the gearinstallation unit 115 provided at the carrier 110. The second planetarygear 130 is meshed with the second ring gear 60 to block the rotation ofthe second ring gear 60.

The second planetary gear 130 is formed at a periphery with a gear tooth131, and is formed at an inner surface with a bearing accommodation hole152 coupled with an outer ring 151 of the bearing 150. A diameter of thebearing accommodation hole 152 is same as that of the outer ring 151 ofthe bearing 151.

Meanwhile, the bearing 150 is provided to minimize a friction generatedwhen the second planetary gear 130 is rotated, and includes an outerring 151 and an inner ring 152. A ball member is interposed between theouter ring and the inner ring 151, 152, and serves to smooth a relativerotation between the outer ring 151 and the inner ring 152.

The inner ring 152 is centrally formed with a bearing pin hole 153having a diameter corresponding to that of the fixing pin 140. Althoughthe present disclosure has exemplified the hearing 150 as a ballbearing, the present disclosure is not limited thereto, and other typesof bearings including an air bearing and a magnetic bearing may be used,when the need arises.

The fixing pin 140 includes a pin body 141 and a pin head 142. The pinbody 141 is insertedly coupled from an inner side toward an outer sideof the pin holes 113 penetratively formed at the gear installation unit115 provided at the carrier 110. At this time, a distal end of the pinhole 113 is formed with a through holes 116 having a diameter smallerthan that of the pin hole 113, such that the fixing pin 140 cannotpenetrate the pin holes 113. Furthermore, the pin head supports theinner ring 152 of the bearing 150 to allow the second planetary gear 130to be supported by the pin head 142 to inhibit from being deviated froman installation position.

The pin body 141 of the fixing pin 140 is penetratively coupled to abearing pin hole 153 centrally formed at the inner ring 152 of thebearing 150 from an upper side to a bottom side, as shown in theexploded perspective view of FIG. 3, to rotatably and supportively fixthe second planetary gear 130. Thus, the second planetary gear 130 canbe rotated at a distal end of one side by the fixing pin 140 coupled tothe pin hole 113, and can be so installed as to be inhibited from beingdeviated.

In order to insert both ends of the pin body 141 of the fixing pin 140to the pin hole 113, there is a need of press-fitting by performing apress-fit process. The need to perform the press-fitting process is toinhibit the press-fitted fixing pin 140 from being easily deviated fromthe pin hole 113.

According to the configuration thus described, the shape of carrier canbe simplified to enable manufacturing of the carrier in various methodsincluding die casting and sintering, and the carrier needs nocomplicated processing after manufacturing, to reduce the cost involvedin parts manufacturing.

Furthermore, although two washer members were needed for each secondplanetary gear 130 according to prior art, the function of washermembers can be replaced by the fact that the support ring 114 integrallyformed with the gear installation unit 115 of the carrier 110 supportsthe inner ring 152 of the bearing 150, such that a total of eight washermembers according to the prior art can be omitted by the presentdisclosure.

As apparent from the foregoing, the planetary gear train fortransmission of e-bike motor according to the present disclosure has anindustrial applicability in that a carrier can be manufactured invarious methods to reduce a manufacturing cost of parts, and to reduceassembleability and parts cost due to reduced number of parts involvedin the assembly.

Although the present disclosure has been described with reference to anumber of illustrative embodiments thereof, it should be understood thatnumerous other modifications and embodiments can be devised by thoseskilled in the art that will fall within the spirit and scope of theprinciples of this disclosure.

More particularly, various variations and modifications are possible inthe component parts and/or arrangements of the subject combinationarrangement within the scope of the disclosure, the drawings and theappended claims. In addition to variations and modifications in thecomponent parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

1. A planetary gear train for transmission of e-bike motor, theplanetary gear train comprising: a first carrier protrusively formed ina center with a stator axis insertion boss provided with a stator axisinsertion groove in a shape corresponding to that of the stator axis forinsertion of the stator axis, and mounted with a plurality of first gearinstallation units; a second carrier formed with a second gearinstallation unit at a position corresponding to that of the first gearinstallation unit of the first carrier, and mounted in a center with aboss insertion hole penetratively coupled by the stator axis insertionboss; a plurality of planetary gears interposed between the first andsecond installation units of the first and second carriers; and a fixingpin rotatably fixing the plurality of planetary gears on the first andsecond gear installation units.
 2. The planetary gear train fortransmission of e-bike motor of claim 1, further comprising a bearingcentrally arranged on the plurality of the planetary gears, where anouter ring is centrally fixed at the planetary gear and an inner ring iscoupled by the fixing pin.
 3. The planetary gear train of claim 2,wherein the first and second gear installation units include first andsecond pin holes each having a diameter corresponding to that of thefixing pin, and first and second support rings protrusively formed at asurface opposite to the planetary gear, and centrally and respectivelyarranged with first and second pin holes.
 4. The planetary gear train ofclaim 1, wherein the planetary gear is centrally formed with a bearingaccommodation hole having a diameter corresponding to that of the outerring of the bearing.
 5. The planetary gear train of claim 4, wherein theinner ring of the bearing includes the fixing pin and a bearing pin holehaving a size corresponding to the diameter of the first and second pinhole coupled to the fixing pin.
 6. The planetary gear train of claim 4,wherein the first and second support rings respectively support theinner ring of the bearing.
 7. The planetary gear train of claim 1,wherein the first and second carriers are provided in a cross (+) shapewith four directions being symmetrical, centrally and respectivelyprovided with the stator axis insertion boss and the boss insertionhole, and the first and second gear installation units are provided atfour protrusive distal ends to allow four planetary gears to berotatably mounted.
 8. A planetary gear train for transmission of e-bikemotor, the planetary gear train comprising: a carrier protrusivelyformed in a center with a stator axis insertion boss provided with astator axis insertion groove in a shape corresponding to that of thestator axis for insertion of the stator axis, and mounted with aplurality of gear installation units; a plurality of planetary gearsinterposed rotatably mounted at an upper surface of the gearinstallation unit of the carrier; and a fixing pin rotatably mountingthe plurality of planetary gears on the gear installation units, whereinthe fixing pin includes a pin head inhibiting the planetary gears fromdeviating.
 9. The planetary gear train of claim 8, further comprising ahearing centrally arranged on the plurality of the planetary gears,where an outer ring is centrally fixed at the planetary gear and aninner ring is coupled by the fixing pin.
 10. The planetary gear train ofclaim 9, wherein the gear installation units include a pin hole having adiameter corresponding to that of the fixing pin, a support ringprotrusively formed at a surface opposite to the planetary gear, andcentrally arranged with the pin hole, and a through hole having adiameter smaller than that of the pin hole and formed with a pin supportunit at a center of the pin hole.
 11. The planetary gear train of claim8, wherein the planetary gear is centrally formed with a bearingaccommodation hole having a diameter corresponding to that of the outerring of the bearing.
 12. The planetary gear train of claim 11, whereinthe inner ring of the bearing includes the fixing pin and a bearing pinhole having a size corresponding to the diameter of the pin hole coupledto the fixing pin.
 13. The planetary gear train of claim 11, wherein thesupport ring supports the inner ring of the bearing.
 14. The planetarygear train of claim 8, wherein the carrier is provided in a cross (+)shape with four directions being symmetrical, centrally provided withthe stator axis insertion boss, and the gear installation unit isprovided at four protrusive distal ends to allow four planetary gears tobe rotatably mounted.